Silencer



F. BOYSEN Aug. 6, 1935.

SILENGER F 15a/SGF? /M/f/l/Ta/Q 5 www 9%@ Y w55" Filed Aug. 8, 1932 Patented Aug. 6, 1935 UNITED STATES PATENT OFFICE to Daimler-Benz Aktiengesellschaft, Stuttgart- Unterturkheim, Germany, a company of Germany Y Application August 8, 1932, Serial No. 627,955

In Germany September 1, 1931 1'2 claims. (cl. la7- 1am This invention relates to a method of silencing the exhaust noises of internal combustion engines, the stream of exhaust gases being divided and caused to flow in two parts alonghelical or 6 spiral paths.

The object of this is for the exhaust gases which emerge.intermittently to bev caught by a gentle, yielding intermixing of the two streams, the so-called wave crests to be absorbed and a steady ilow of exhaust gases to be produced. Throttling places which would detrimentally affeet the power of the Amotor, special expansion chambers which would considerably increase the size of the exhaust box and separate arrangements such as water injection devices or the like can be avoided. At the same time almost complete noiselessness of the exhaust is ensured.

The method in its eiectiveness thus surpasses all methods used hitherto, which have one fault or another as regards the requirements as to lower losses, noiselessness, space occupied or the like, and provides at the same time, for instance for low frame vehicles, the advantage that even with thoroughly effective silencingan excessive- 1y large exhaustbox is avoided and the prescribed height above the ground can be adhered to without the construction suiering. This also does away with a too great development of heat, such as easily occurs for instance with large Lexvhaust boxes. rI'he invention also provides a method through which by the peculiar way of guiding `the streams of gas and more particularly by the peculiar iormation of the separating walls particularly suitable and s ace economizing constructions become possib e. u

In the drawing a constructional example of the invention is illustrated, i g

Fig.w 1 being a longitudinal section through an silencer,

Fig. 2 a longitudinal section perpendicular to that oi Fig. 1, on line 2 2 of Fig. 1 viewed in the direction o1' the arrows, A

Fig. 3 a cross-section on line 3 3 in Fig. 1,

Fig. 4 a cross-section on line 4 4 in Fig. 1,

Eig. 5 a cross-section on line 5 5 in Fig. 1,

Fig. 6 a cross-section on line 6 6 in Fig. 1,

Fig. '7 a cross-section on line 1 1 in Fig. 1.,

Fig. 8 a cross-section ori line 8 8 in Fig. l.

a is the exhaust pipe which is-connected up to the engine and to the exhaust silencer and c the outlet pipethrough which the exhaust gases pass into the atmosphere. The silencer comprises a tubular casing b havinga tube d, d therein which extends axially from the inlet end of the silencer to a transverse wall h and divides the silencer into a tubular inner chamber and an outer annular chamber II, a portion of the side d of said .tube beingfcut aw'ay at the ends e and e. Within the tube d, d is a wall f ci 5 semi-circular cross-section which extends longitudinally in proximity to the side d' from the inlet end of the silencer to the wall h and a wall g which extends substantially diagonally across the space formed between the wall f and the side, d being'in Contact with the wall f at the inlet end of the silencer and extending to the wall h in close proximity to the'side d of the tube d, d. The transverse wall h has an opening therein which establishes communication between the space IV enclosed between the Walls g and f and a-conical outlet piece i connected to the wall h.

By means of this arrangement of walls, a number of spaces -is formed in the interior of the silencer through which the exhaust 4gases pass successively. From theA pipe a the gases pass first into the gradually tapering space I between the side d and the wall g, said space communicating with the annular chamber II through two nozzles k and k extending helically with respect to the axis of the tube d, d'. These nozzles are provided on the tube d, d arranged in proximity to the opposite ends on the side d of thetube d, d with their outlets facing away from the ends of the silencer and oppositely directed. The gases ilowing into the space I pass in part through the nozzle k and in part through the nozzle k' and the two streams of gases passed through these nozzles flow towards one another from opposite directions along helical paths having the same handed twist. This causes a mutual penetration of the streams iiowing past one another with great velocity in the chamber II, whereby the so-called wave crests of the intermittently leaving exhaust gases are destroyed. 'I'he thorough intermingling of the evenly divided column of exhaust gases, to which the abovementioned helical motion is imparted, has a soft and cushioning effect and stabilizes the column of exhaust gases to such an extent that the differently superposed sounds are smoothed out.

' The column of exhaust gases passes out in the form of a uniformly iiowing medium at both ends of the space II through the openings between the wall h and 'the ends e and e' into the equalizing space III between the part d of the wall d, d and the wall'f, in which space the expansion can take place.

As iigures 3 to-7 show, this space III has .a half ring-shaped @ross-section and communicates'through two rows of slot-shaped openings whole length ofthe space, with the inner space IV, which diverges towards the outlet end of the silencer, so that it is possible to obtain a vsteady unthrottled passage of the gases from the space III into the space IV. The wall 9' separating the space IV from the space I is so constructed that its longitudinal edges which are connected to the wall d, d surrounding it lie in one longitudinal central plane, while intermediately of its edges the wall is curved, the degree of curvature decreasing from the ends towards the middle of the silencer at which the direction of curvature reverses. On the left hand side of the silencer the curved part of the wall gis substantially concentric with the side d', While on the right hand side it is substantially parallel to the side d of the tube d, d.

In order to enable the ow of exhaust gases to be discontinued without noise due to the collapse of the column of gases flowing from the silencer and the subsequent entry of air through the silencer exit, the spaces I to IV are followed by a subsequent silencing space V. The exhaust gases pass out of the gradually and uniformly diverging space IV into the conical outlet piece i and through two nozzles m and'm' thereon into the space V'in such a manner that they flow through the latter with a steady rotary motion.

Through the outlet opening 11, the exhaust gases emerge into the actual outlet pipe c, con-- nected eccentrically to the space V from which they pass into the open air. In detail the construction rnay of course diifer from the described example.

Even when the arrangement and construction of the nozzles is made such, for instance according to the constructonal example, that sooting` up and a consequent irregularity in the operation ls avoided, it nevertheless occurs in practice very frequently that vehicles are fitted with a badly regulated engine, which is either fed with a too rich mixture or in any case has a poor combustion, and that in such cases after being in operation for an extended period a sooty deposit on the walls and in 'the passages of the exhaust cannot be avoided. For this reason the silencer is preferably made capable of being taken apart, the arrangement being such that, by removing the covers of the tubes at the inlet and outlet end, the interior is made readily accessible and the sooty deposit can bequickly removed. Provision may be made for a further division of the exhaust box,'for instance at h, in which case the. nozzle-shaped cover i may form a separate piece.

Such silencers can be of exceptionally small dimensions, for instance the diameter of the exhaust box may with advantage Ibe onlyabout twice as great as that of the exhaust pipe.

What I claim is:

1. An exhaust silencer, comprising in combination a tubular casing having an outlet, a tubular concentric conduit inside said casing having a primary inlet for receiving combustion gases from an internal combustion engine, said conduit having two nozzles on one side thereof, in proximity to the opposite ends of the conduit extending helically with respect to the axis of the conduit said nozzles being arranged on one side of the conduit to deliver combustion gases passed into the conduit in two streams flowing towards one another into the annular space between said conduit and casing, said conduit having secondary inlet at its ends on the side of the conduit remote J I from said'nozzles, a wall inside said conduit having a cross-section of arcuate shape interposed between the said two sides of the conduit so as to form with the side of the conduit having the secondary inlets a compartment of semi-annular cross-section isolated from the primary inlet and nozzles, a second wall inside said conduit between said rst-rhentioned wall and the side of the compartment having the nozzles, said second wall being curved intermediately of its longitudinal edges, the degree of curvature decreasing from the ends towards thev middle of the silencer in which the direction of curvature reverses, so that the compartment having theV nozzles gradually g vformed between the two walls having a conical outlet part in communication with the outlet in the silencer casing and the Wall of arcuate shape having inlets distributed over its entirelength for establishing communication between the compartment of semi-annular shape and the compartment having the conical outlet part.

2. An exhaust silencer, comprising in combination a casing having an outlet and aconduit inside said casing, said conduit having an inlet for receiving combustion gases from an internal combustion engine and two nozzles in proximity to its opposite ends, said nozzles being inclined helically with respect to the axis of the conduit and arranged to deliver combustion gases from the conduit to the casing in two streams flowing to- Wards one another in helical paths having the same handed twist so as to screw into one another prior to passing out of the casing through 'the outlet thereof.

3. An exhaust silencer, comprising in combination a casing, a conduit inside said casing, a wall inside said conduit arranged so as to divide ,the conduit into two compartments, a primary inlet in open communication with one of said compartments for admitting combustion gases from an internal combustion engine to said compartment, two nozzles in open communication with said compartment on the side of the conduit in proximity to the opposite ends thereof, said nozzles being inclined helically with respect to the axis of the conduit and arranged to deliver combustion gases from the conduit to the casing in two streams flowing towards one another in helical paths having the same handed twist towards the opposite ends of the casing, said conduit having also secondary inlets for establishing communication between the casing and the other compartment for admitting the combustion gases from the casing to the said compartment and an outlet for the combustion gases in communication with the second mentioned compartment.

4. An exhaust silencer, comprising in combination a casing, a conduit inside said casing, a wall inside said conduit arranged so as to divide the conduit into two compartments, a primary inlet in open communication with one of said compartments for admitting combustion gasesy two streams flowing towards one another in helical paths having the same handed twist towards the opposite ends of the casing, said conduit having also secondary inlets at its ends for establishing communication between. the casing and the other-compartment for admitting the combustion gases from the casing to the said compartment and an outlet for the combustion gases in communication with the second mentioned compartment.

5. An exhaust silencer, comprising in combination a casing, a conduit inside said casing, a wall inside said conduit arranged so as to divide the conduit into two compartments, a primary inlet in open communication with one of said compartments for admitting combustion gases from an internal combustion engine to said last mentioned compartment, two nozzles in open communication with sai-d last mentioned compartment on the side of the conduit in proximity to the opposite ends thereof, said nozzles being inclined helically with respect to the axis of the conduit and arranged to deliver combustion gases from the conduit to the casing in two streams flowing towards one another in helical paths having the same handed twist towards the opposite ends of the casing, said conduit having also secondary inlets for establishing communication between the casing and the other compartment for admitting the combustion gases from the casing to the said compartment, a wall inside the conduit extending diagonally therein from the first-mentioned wall to the side of the conduit on which the nozzlesv are located so as to divide said compartment into two compartments, one in communication with the nozzles and the other isolated therefrom, the latter..of said two compartments having an outlet and the first-mentioned wall having inlets therein distributed over .its entire length for establishing communication between the compartment having the said outlet and the secondary inlets.

v6. An exhaust silencer, comprising in combination a casing, a conduit inside said casing, a wall'inside said conduit arranged so as to divide the conduit into two compartments, a second wall inside one of said compartments arranged so as to divide said compartment into two sub-compartments, a primary inlet in open communication with one of said sub-compartments for admitting combustion gases from an internal combustion engine to said sub-compartment,twonozzles in open communication with said sub-compartment on. the side of the .conduit in proximityto the opposite ends thereof, said nozzles being inclined helically with respect to the axis of the conduit and arranged to deliver combustion gases from the said sub-compartment to the casing in two streams flowing towards one another in helical paths having the same handed twist towards the opposite ends of the casing said conduit having also secondary inlets at its er1-ds for establishing communication between the casing and the other compartmentJ for admitting the combustion gases from the casing to said compartment. the other sub-compartment having an outlet and the rstmentioned wall having inlets therein distributed over its entire lengtxrfor establishing communication between said other compartment and other sub-compartment.

'7. An exhaust silencer comprising the combi.

nation as set forth in ciaim 3 with a subsequent silencing chamber, having an outlet and the outlet of the conduit comprising a plurality of noz zles arranged to discharge the combustion gases to said subsequent silencing chamber.

8. An exhaust silencer as set forth in claim 6, in which the second wall extends longitudinally of the conduit and is curved intermediately of its longitudinal edges, the degree of curvature decreasing from its ends towards the middle of the'conduit and reversing. so that the sub-compartment which receives the combustion gases from the primary inlet gradually decreases in cross-section from the primary inlet towards the end of the sub-compartment remote from the primary inlet.

9. An exhaust silencer comprising the combination as set forth in claim 3 with a subsequent silencing chamber having an outlet offset with respect to the outlet for the combustion gases in communication with the second-mentioned compartment of the conduit.

l0. An exhaust silencer as set forth in claim 3 in which the outlet in communication with the second mentioned compartment ofthe conduit comprises a conical outlet part having a plurality of discharge nozzles extending substantially over the entire length of the conical outlet part, the silencer casing having an internal end wall spaced from the end of the casing to form a subsequent silencing space, said conical outlet part and discharge nozzles being arranged in said silencing space.

11. An exhaust silencer as set forth in claim 3 in which the outlet in communication with the second mentioned compartment of the conduit comprisesa conical outlet part having a plurality of tangential discharge nozzles extending substantially cver the entire length of the conical outlet part, the silencer casing having an internal end wall spaced from the end of the casing to form a subsequent silencing space, said conical outlet part and discharge nozzles being arranged in said silencing space.

12. An exhaust'silencer, comprising in combination acasing, a conduit for receiving combustion gases from an internal combustion engine, said casing having an outlet therein and said conduits having two nozzles in proximity to the opposite ends of the casing extending helically with respect to the axis of the casing, said nozzles being connected to said conduit and arranged to deliver combustion gases passed into the conduit in two streams flowing towards one another into the said casing in two streams which are constrained to ow inside the casing along helical paths having the same handed twist so as to screw into vone another prior to passing out of the casing through the outlet. 

